The perception of disease risk, the personal belief about the probability of developing disease, is one of the most frequently utilized factors in health behavior change theories. Cancer-related risk perception is an important prerequisite for varied cancer screening and prevention behaviors. As such, the unprecedented advancements in the role of lifestyle, genetics, and environment in the etiology of cancer necessitate further examination of the process by which individuals gather and use cancer risk information. Despite the importance of cancer-related risk perception in cancer control, current measurement methods are widely criticized. Criticisms include lack of established reliability and validity, and the predominant use of likelihood scales. The goal of the study is to develop and provide initial evidence for the reliability and validity of a measure of cancer-related risk perception. Given that tobacco use is the paramount cancer risk factor, we will use smokers' conceptions of their cancer risk as a basis for the initial development of the measure. First, we will generate a cancer-related risk perception item pool based on a review of the literature, and interviews with healthy, . ethnically diverse smokers. Second, we will conduct qualitative and quantitative analyses of the items through focus groups and smokers' (N=200) survey responses. Finally, we will construct a cancer-related risk perception scale and establish reliability and construct validity of the reduced item pool using an additional sample of smokers (N=200). The development of a cancer-related risk perception scale would allow for more accurate assessment of the impact of cancer risk information, and more precise testing of risk perception as a mediator of behavior change. It would also provide a basis for standardized comparison of risk perceptions across a variety of cancer sites with diverse populations.